This invention relates generally to door operators, and more particularly to a door operator for selectively automatically or manually opening a door.
The purpose of door operators is to open and close a door. Automatic door operators are used on public buildings and residences to allow for access by the physically disabled or where manual operation of the door may be inconvenient to users. In public facilities, it is a required American National Standard that doors which provide ingress and egress have the ability to open automatically in order to allow handicapped people passage through the doorway.
A variety of electromechanical automatic door operators are known. A typical door operator includes an electric motor and a linkage assembly for operatively coupling the drive shaft of the motor to a door so that the door will be opened and closed when the drive shaft rotates. Activation of the door operator is initiated by means of an electric signal generated in a variety of ways such as, for example, a pressure switch, an ultrasonic or photoelectric presence sensor, motion sensors, radio transmitters, wall switches, and the like. The door may then be closed under power or with a door closer. A conventional door closer uses an internal spring mechanism which is compressed during the opening of the door for storing sufficient energy so that the door can be returned to a closed position without the input of additional electrical energy. In the some door operators, the automatic, powered opening system is still engaged so that the spring force of the door closer must overcome the resistance caused by counter-rotating the gear train coupled to the motor. Since this spring force must be large, an individual manually opening the door must exert substantial force to overcome the spring force and the resistance forces generated by the opening system. Moreover, driving the components of the powered opening system during manual opening and closing of the door causes the gear train to become worn more quickly over time.
Some door operator systems are provided with clutch mechanisms between the motor and the linkage assembly that enable the door to be moved freely under manual power. Various clutching mechanisms decouple powered opening system during the closing cycle, which is particularly necessary in the event of an interruption of power supply. This solution still presents problems. For example, a door operator utilizing a slip clutch or the like will create some drag or resistance when the door is manually opened or closed. Moreover, conventional clutch mechanisms which do not create resistance suffer from a limited range of motion.
For the foregoing reasons, there is a need for a door operator which allows for selective automatic or manual door operation wherein manual opening and closing of the door does not engage any of the components within an automatic powered door opener, allowing the user to pass through the door as though the door were not equipped with the door operator. The new door operator should function with various combinations of door configurations, including push and pull side applications and right-hand and left-hand doors. Ideally, the new door operator would be adapted for use with existing door construction.